We often talk of dividing as being the reverse of multiplying, and indeed when dividing fractions this is the case. The way you divide fractions is very similar to the way fractions are multiplied with a simple twist in the middle.
If a child is really confused about decimals, converting decimal numnbers into money is a great way to make things clearer. For example: a child may be asked to say how much bigger 1.3 is than 0.9. If they convert these decimals into money (£1.30 and 90p) they may find that they can do this calculation very quickly in their head, getting the answer 40p which they convert back into the decimal, 0.4. Demonstrating that money maths depends on decimal understanding is also an easy way to prove that decimals are actually useful in real life!